Cordless power tools provide many advantages to traditional corded power tools. In particular, cordless tools provide unmatched convenience and portability. An operator can use a cordless power tool anywhere and anytime, regardless of the availability of a power supply. In addition, cordless power tools provide increased safety and reliability because there is no cumbersome cord to maneuver around while working on the job, and no risk of accidently cutting a cord in a hazardous work area.
However, conventional cordless power tools still have their disadvantages. Typically, cordless power tools provide far less power as compared to their corded counterparts. Today, operators desire power tools that provide the same benefits of convenience and portability, while also providing similar performance as corded power tools.
Brushless DC (BLDC) motors have been used in recent years in various cordless power tools. BLDC motors offer many size and power output advantages over universal and permanent magnet DC motors. BLDC motors are electronically-controller via a programmable controller, and thus do not suffer from many mechanical failures associated with universal motor.
Since BLDC motors are electronically commutated, the controller can also brake the motor electronically. Braking the motor brings it to a quick stop, rather than allow it to coast down. Conventional motor brakes involved complex mechanical components, which are no longer needed when braking the motor electronically. Electronic braking provides many advantages over conventional brakes. However, the way the motor voltage affects the rest of the power tool circuit should be accounted for when executing electronic braking. What is needed is a system and mechanism that allows for effective execution of electronic braking without jeopardizing the performance of the rest of the power tool.